Sinh học - Chapter 56: Conservation biology and global change

Ch. 56 Warm-UpHow does acid precipitation affect the environment?Explain how the greenhouse effect can be both positive and negative.Should humans be concerned about biological magnification? Explain.Define Ch. 56 Terms:EutrophicationBiological magnificationGreenhouse effectGlobal warmingAcid precipitationChapter 56: Conservation Biology and Global ChangeWhat you need to know:The value of biodiversity, and the major human threats to it.How human activity is changing the earthBiodiversityConservation biology is a goal-oriented science that seeks to counter the biodiversity crisis, the current rapid decrease in Earth’s variety of life.Extinction is a natural phenomenon that has been occurring since life evolved on earth.The current rate of extinction is what underlies the biodiversity crisis.A high rate of species extinction is being caused by humans.The three levels of biodiversity:genetic diversityspecies diversityecosystem diversityThe four major threats to biodiversity:Habitat lossHuman alteration of habitat is the single greatest threat to biodiversityIntroduced species: invasive/nonnative/exotic speciesOverexploitation: harvest wild plants/animalsGlobal change: alter climate, atmosphere, & ecological systems  reduce Earth’s capacity to sustain lifeMovement corridors can promote dispersal if habitats are fragmentedLandscape conservationBiodiversity Hot SpotsExcess nitrogen from agriculture enters aquatic ecosystemsAlgae and bacteria bloom/die  reduce oxygen  fish and invertebrates dieEutrophicationMississippi basin dead zone (red)Acid PrecipitationRain, snow, or fog with a pH less than 5.6Caused by burning of wood & fossil fuels  release sulfur oxides and nitrogen oxidesReact with water in the atmosphere to produce sulfuric and nitric acidsThe effects of acid precipitation on a forestAcid rain damage to statuary, 1908 & 1968Toxins become more concentrated in successive trophic levels of a food webToxins can’t be broken down & magnify in concentration up the food chainProblem: mercury in fishBiological MagnificationHuman activities are depleting the atmospheric ozoneLife on earth is protected from the damaging affects of ultraviolet radiation (UV) by a layer of O3,or ozone.Chlorine-containing compounds erode the ozone layerGreenhouse EffectGreenhouse Effect: absorption of heat the Earth experiences due to certain greenhouse gasesCO2 and water vapor absorb infrared radiation and re-reflect back toward EarthThe Earth needs this heat, but too much could be disastrous.Rising atmospheric CO2Since the Industrial Revolution, the concentration of CO2 in the atmosphere has increased greatly as a result of burning fossil fuels.Global Climate Change (“Global Warming”)Studies predict a doubling of CO2 in the atmosphere will cause a 3ºC increase in the average temperature of Earth.Rising temperatures could cause polar ice cap melting, which could flood coastal areas.Approach: stabilize use of fossil fuels and reduce deforestationGlobal Climate ChangeSnow and rainfall patterns shiftingFloods, drought, intense rainfall, more frequent and severe heat wavesNASA Video Clip: Daily Arctic Sea Ice Changes